The present invention relates to gas turbine engines and, more particularly, is concerned with a diffuser-burner casing forming a structural member between the compressor section and the turbine section of such an engine.
Gas turbine engines are now widely used as power sources in both stationary and moving environments. For example, it is common to utilize industrial gas turbine engines as the power sources in an electric power plant. Even more common is the use of gas turbine engines as the power plants for large vehicles such as airplanes. A relativly common design for such gas turbine engines is the axial flow engine in which air is ingested through an inlet at the front of the engine an moves generally axially through a compressor section, a combustion section, where the fuel and air mix and burn, and a turbine section in which the burning gases drive single or multistage turbines before being expelled through an exhaust diffuser at the rear of the engine. In turbojet engines such as used in jet aircraft, the exhaust gases are used primarily to develop thrust; whereas in industrial engines the exhaust gases drive a power turbine having a mechanical output connected to a power absorbing device such as an electrical generator.
In gas turbine engines producing either thrust or mechanical output, the combustion or "hot" section of the engine, should be designed to take into consideration many factors. There is substantial thermal stressing within the engine casing in the area of the burners and compressor diffuser because the combustion process is continuous and produces intense heat at some local regions within the casing while other regions are maintained relatively cool by the continuous flow of air from the compressor diffuser to the burners in the combustion chamber assemblies. The diffuser-burner casing also serves as a structural member between the compressor and turbine sections and hence transmits axial loads between the compressor at the front of the engine and the turbine at the rear of the engine. Additionally, one or more drive shafts may extend through the diffuser-burner casing to transmit power from turbines to the various compressors or fans in the forward part of the engine. Hence, the diffuser-burner casing may provide support for shaft bearings in the midportion of the engine. Still further, the casing may cooperate with the compressor by defining the diffuser geometry and the air flow path between the diffuser and the combustion chamber assemblies. That flow path should promote uniform diffusion and distribution of air from the compressor to the combustion chamber assemblies for most efficient mixing and burning in the various combustion chamber assemblies. In addition to all of the above features, it is desirable that maintenance and servicing of the "hot" section of the engine be carried out with minimum time and effort. Thus, the design of the casing in the vicinity of the combustion section is of special interest and importance to the overall functioning and operation of the turbine engine.
It is, accordingly, a general object of the present invention to provide a diffuser-burner casing having all of the above features in the area of the combustion section of a gas turbine engine.